1. Field of the Invention
The present invention relates to a multi-phase bipolar brushless D.C. motor in which a stator is constituted by an armature and a rotor is constituted by permanent magnets.
If in this motor the stator winding is arranged as the lap winding, the motor produces the sinusoidal torque ripples thereby to be adapted for the micro-motor, and instead if the stator winding is arranged as the wave winding, the motor produces the trapezoidal torque ripples thereby to be adapted for the power motor.
And this invention is devised to make into the bipolar system so that the copper loss of the exciting coil can be minimized, thereby increasing the efficiency, and to make into polyphase so that the utility of the coil can be increased, thereby making the compact design of the motor possible and improving the torque ripple. Also in this motor the commutation system comprising a commutation encoder, a photo-sensor and a electronic commutator is simply and safely constituted so that the starting and rotation characteristics of the motor can be improved as well as the motor having the simple construction can be manufactured, thereby reducing the cost of production.
2. Description of the Prior Art
In a conventional shunt motor, since the field coils (exciting coils) are wound on the rotor to have the proper number of poles and the coils attaching the brushes thereto are wound on the rotor so that the rotor is rotated, there are drawbacks that, during its use, the alien substances such as dusts are jammed between the commutator segments or the brush must be replaced with the new one due to the contact therebetween by breakdown of insulation or the wear thereof.